code: def test_iadd(self, container, lst):
      q = r = container
  
      q += [5]
      self.check_result(q, lst + [5])
  
      # Other shouldn't be mutated.
      self.check_result(r, lst)
  
file_path: pandas/pandas/tests/indexes/test_frozen.py
imports: import re
  import pytest
  from pandas.core.indexes.frozen import FrozenList
label_desc: Use image node_id 8 for calling the TestFrozenList obj's underlying member method code with example usage: obj.test_iadd(container, lst) without return types